1. Field of the Invention
The invention relates to chemical devices, methods for manufacturing chemical devices and methods for use with chemical devices. The term xe2x80x9cchemical devicesxe2x80x9d is used in this specification to include devices used for performing chemical reactions (including biochemical reactions) and/or for performing analysis and separation of chemical (including biochemical) substances. Such analysis and separation of chemical substances may or may not include performing chemical reactions.
2. Description of Related Art
A known type of chemical device is a chip-type chemical device. A chip-type chemical device is formed from a first member (usually a plate of glass, metal, polymer, silicon or quartz) that has a surface portion and at least one groove (more usually a plurality of interconnected grooves) located at the surface portion, and a second member (usually a block formed of glass, metal, polymers silicon or quartz) having a co-operating surface portion. The surface portions are connected together such that the groove (or the plurality of interconnected grooves) is closed to form a channel (or a plurality of interconnected channels). Reagents and other chemical substances may be passed through the channel (or the plurality of interconnected channels) in a controlled manner so as to perform chemical reactions, or analysis or separation of chemical substances. One method of causing liquid reagents (including solutions) to move through channels of chemical devices is to induce an electroosmotic force by applying a voltage. A discussion of this is provided in an article by S.J Haswell entitled xe2x80x9cDevelopment and Operating Characteristics of Micro-Flow Injection Analysis Systems based on Electroosmotic Flowsxe2x80x9d in Analyst, January 1997, vol.122 (1R-10R), which article is incorporated herein by reference.
For most purposes, the current preferred method of connecting the surface portions of glass members is by heating the members to a temperature close to their upper annealing temperature while the surface portions are contacting one another. This results in direct thermal connection (also called thermal bonding or annealing) of the surface portionsxe2x80x94that is to say direct thermally induced bonding together of the surface portions without any intervening link or extraneous adhesive.
In accordance with a first aspect of the invention, there is provided a method of manufacturing a chemical device comprising, providing a first member with a surface portion and a groove located at the surface portion, a second member with a surface portion, and means heatable by electromagnetic irradiation, positioning the members and the means so that the means lies between the surface portions, aid heating the means by electromagnetic irradiation to effect or assist linking of the surface portions by the means so as to close the groove to form a channel. In accordance with a second aspect of the invention, there is provided a method of manufacturing a chemical device comprising, providing first and second members having respective surface portions, and means heatable by electromagnetic irradiations positioning the members and the means relative to one another so that the means is positioned for providing localised heating of at least one of the surface portions on heating of the means by electromagnetic irradiation, irradiating with electromagnetic radiation so as to cause said localised heating, and connecting the surface portions together so that the surface portions cooperate to define a channel, the localised heating effecting or assisting said connection.
According to a third aspect of the invention, there is provided a chemical device comprising a first member with a surface portion and a groove located at the surface portion and a second member with a surface portion, the surface portions being linked by an electromagnetic irradiation heatable layer such that the groove is closed to form a channel.
According to a fourth aspect of the invention, there is provided a method of controlling liquid movement in a chemical device comprising a porous structure, the method comprising applying an electrical potential to generate an electroosmotic force in the porous structure so as to propel a liquid through the porous structure, and using the porous structure to resist or prevent flow of a liquid through the porous structure in response to hydrostatic force.
Controlling the flow of liquids in this way may be used to reduce or prevent undesired flow and mixing of liquids due to hydrostatic force.
According to a fifth aspect of the invention, there is provided a method of preparing a working solution of a substance at a desired concentration in a chemical device comprising, providing a substance in a soluble form in a chemical device, contacting the substance with a solvent for the substance in the device, and controlling said contact between the substance and the solvent so as to produce a working solution of the substance in the solvent at a concentration dependent on said control.
The ability to prepare working solutions of a desired concentration in this way may be useful when it is not practicable to introduce externally prepared working solutions into the chemical device. This may be of utility in applications such as environmental monitoring, where chemical devices are required to perform monitoring operations repeatedly over some length of time without external maintenance.